Remove some archived proposals from this repository

[alexcrichton]

This commit removes the test suite mirror for the following proposals:

• exception-handling
• extended-const
• function-references
• gc
• multi-memory
• tail-call

These proposals have all been merged into the wasm-3.0 branch of the specification and their corresponding proposal repositories have all been archived. My assumption is that this means that the source of truth for these specifications now lives in the wasm-3.0 branch and thus don't need to be doubly-included as those tests are already included.

[tlively]

LGTM. Any concerns @titzer?

[alexcrichton]

I'm gonna go ahead and merge this, but happy to revert and/or have follow-ups as necessary.

[andreaTP]

Hi 👋 !
In chicory we use to rely on the folder separation during implementation of the features.
We can pin the testsuite to an older commit until we have full implementations of the proposals, the major struggle is that, now, it becomes harder to implement features in isolation.

How the tests are shaped is(often) with most passing tests in a single wasm payload, if that one requires multiple proposals to be available it becomes harder to work iteratively.

I see that, in some cases, files has been renamed but left separated (e.g. binary.wast and binary0.wast) what's the rationale?
Anything I'm overlooking?

[alexcrichton]

This repository is only a reflection of the testsuite in upstream repositories, so questions about naming and test organization is best for the spec/repositories themselves. The repositories removed here have all been archived as their tests are included upstream in the wasm-3.0 branch.

Personally I share concerns about how it's difficult to implement a proposal-at-a-time after the fact, but that's something I'd recommend raising on the spec repo rather than here.